This paper investigates performance, power and energy efficiency of several
CMOS master-slave D-flip-flops (DFF's). To improve performance and energy
efficiency, a push-pull DFF and a push-pull isolation DFF are proposed, Amo
ng the five DFF's compared, the proposed push-pull isolation circuit is fou
nd to be the fastest with the best energy efficiency, Effects of using a do
uble-pass-transistor logic (DPL) circuit and tri-state push-pull driver are
also studied, Last, metastability characteristics of the five DFF's are al
so analyzed.